Inhibition of Crystallite Growth in the Sol-Gel Synthesis of Nanocrystalline Metal Oxides

Abstract

Crystal growth upon firing of hydrous transition metal oxide gels can be effectively inhibited by replacing the surface hydroxyl group before firing with another functional group that does not condense and that can produce small, secondary-phase particles that restrict advancing of grain boundaries at elevated temperatures. Accordingly, fully crystallized SnO(2), TiO(2), and ZrO(2) materials with mean crystallite sizes of approximately 20, 50, and 15 angstroms, respectively, were synthesized by replacing the hydroxyl group with methyl siloxyl before firing at 500 degrees C. An ultrasensitive SnO(2)-based chemical sensor resulting from the microstructural miniaturization was demonstrated.

Carbon Nanotubes and Carbon Nanotubes/Metal Oxide Heterostructures: Synthesis, Characterization and Electrochemical Property

“…So, There is also important significant for fuel cell and biosensor to study further electrocatalysis of CNTs/metal oxide or hydroxide composites. [216,217], while SnO 2 is sensitive to NOx, CO, ethanol, and C 2 H 4 [218]. However, their sensing properties often suffer degradation due to growth and aggregation.…”

The Review of Semiconductor Gas Sensor for Nox Detcting

“…Adding a secondary component as dopant or surface additive can dam the SnO 2 grain growth at calcination temperature 700 °C and improve the performance of SnO 2 gas sensors, especially for reducing gases (N.-L. Wu, Wang, & Rusakova, 1999;C. Xu, Tamaki, Miura, & Yamazoe, 1991).…”

Transformation of β-Ni(OH)2to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

“…Pang et al showed the size of SnO 2 nanoparticles could be controlled as small as 3.5 nm even heat treatment at 600°C [3]. Wu et al found that surface-modified methylsiloxyl groups on the metal oxide gel could prevent grain growth of metal oxides during high temperature treatments and excellent gas sensing properties were shown [4]. Lyu et al also showed that the thermal stabilities of mesoporous metal oxides were improved by introducing silicon-contained hybrid Gemini surfactants as a nano-propping agent [5].…”

“…In order to preserve nanostructured natures of materials at elevated temperatures, retardation of sintering behaviors was considered. However, only few reports emphasized stabilization of the nanostructured materials at high temperatures [1][2][3][4][5]. Pang et al showed the size of SnO 2 nanoparticles could be controlled as small as 3.5 nm even heat treatment at 600°C [3].…”